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nfsd: add some comments to the nfsd4 object definitions 

Add some comments that describe what each of these objects is, and how
they related to one another.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
hifive-unleashed-5.1
Jeff Layton 2014-08-05 15:13:30 -04:00 committed by J. Bruce Fields
parent b687f6863e
commit 14a571a8ec
2 changed files with 101 additions and 7 deletions
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8
fs/nfsd/netns.h
View File

@ -34,6 +34,14 @@
struct cld_net;
struct nfsd4_client_tracking_ops;
/*
* Represents a nfsd "container". With respect to nfsv4 state tracking, the
* fields of interest are the *_id_hashtbls and the *_name_tree. These track
* the nfs4_client objects by either short or long form clientid.
*
* Each nfsd_net runs a nfs4_laundromat workqueue job when necessary to clean
* up expired clients and delegations within the container.
*/
struct nfsd_net {
struct cld_net *cld_net;

100
fs/nfsd/state.h
View File

@ -72,6 +72,11 @@ struct nfsd4_callback {
bool cb_done;
};
/*
* A core object that represents a "common" stateid. These are generally
* embedded within the different (more specific) stateid objects and contain
* fields that are of general use to any stateid.
*/
struct nfs4_stid {
atomic_t sc_count;
#define NFS4_OPEN_STID 1
@ -89,6 +94,27 @@ struct nfs4_stid {
void (*sc_free)(struct nfs4_stid *);
};
/*
* Represents a delegation stateid. The nfs4_client holds references to these
* and they are put when it is being destroyed or when the delegation is
* returned by the client:
*
* o 1 reference as long as a delegation is still in force (taken when it's
* alloc'd, put when it's returned or revoked)
*
* o 1 reference as long as a recall rpc is in progress (taken when the lease
* is broken, put when the rpc exits)
*
* o 1 more ephemeral reference for each nfsd thread currently doing something
* with that delegation without holding the cl_lock
*
* If the server attempts to recall a delegation and the client doesn't do so
* before a timeout, the server may also revoke the delegation. In that case,
* the object will either be destroyed (v4.0) or moved to a per-client list of
* revoked delegations (v4.1+).
*
* This object is a superset of the nfs4_stid.
*/
struct nfs4_delegation {
struct nfs4_stid dl_stid; /* must be first field */
struct list_head dl_perfile;
@ -195,6 +221,11 @@ struct nfsd4_conn {
unsigned char cn_flags;
};
/*
* Representation of a v4.1+ session. These are refcounted in a similar fashion
* to the nfs4_client. References are only taken when the server is actively
* working on the object (primarily during the processing of compounds).
*/
struct nfsd4_session {
atomic_t se_ref;
struct list_head se_hash; /* hash by sessionid */
@ -224,13 +255,30 @@ struct nfsd4_sessionid {
/*
* struct nfs4_client - one per client. Clientids live here.
* o Each nfs4_client is hashed by clientid.
*
* o Each nfs4_clients is also hashed by name
* (the opaque quantity initially sent by the client to identify itself).
* The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
* or EXCHANGE_ID (for NFSv4.1+). These objects are refcounted and timestamped.
* Each nfsd_net_ns object contains a set of these and they are tracked via
* short and long form clientid. They are hashed and searched for under the
* per-nfsd_net client_lock spinlock.
*
* References to it are only held during the processing of compounds, and in
* certain other operations. In their "resting state" they have a refcount of
* 0. If they are not renewed within a lease period, they become eligible for
* destruction by the laundromat.
*
* These objects can also be destroyed prematurely by the fault injection code,
* or if the client sends certain forms of SETCLIENTID or EXCHANGE_ID updates.
* Care is taken *not* to do this however when the objects have an elevated
* refcount.
*
* o Each nfs4_client is hashed by clientid
*
* o Each nfs4_clients is also hashed by name (the opaque quantity initially
* sent by the client to identify itself).
*
* o cl_perclient list is used to ensure no dangling stateowner references
* when we expire the nfs4_client
* o cl_perclient list is used to ensure no dangling stateowner references
* when we expire the nfs4_client
*/
struct nfs4_client {
struct list_head cl_idhash; /* hash by cl_clientid.id */
@ -340,6 +388,12 @@ struct nfs4_stateowner_operations {
void (*so_free)(struct nfs4_stateowner *);
};
/*
* A core object that represents either an open or lock owner. The object and
* lock owner objects have one of these embedded within them. Refcounts and
* other fields common to both owner types are contained within these
* structures.
*/
struct nfs4_stateowner {
struct list_head so_strhash;
struct list_head so_stateids;
@ -354,6 +408,12 @@ struct nfs4_stateowner {
bool so_is_open_owner;
};
/*
* When a file is opened, the client provides an open state owner opaque string
* that indicates the "owner" of that open. These objects are refcounted.
* References to it are held by each open state associated with it. This object
* is a superset of the nfs4_stateowner struct.
*/
struct nfs4_openowner {
struct nfs4_stateowner oo_owner; /* must be first field */
struct list_head oo_perclient;
@ -371,6 +431,12 @@ struct nfs4_openowner {
unsigned char oo_flags;
};
/*
* Represents a generic "lockowner". Similar to an openowner. References to it
* are held by the lock stateids that are created on its behalf. This object is
* a superset of the nfs4_stateowner struct (or would be if it needed any extra
* fields).
*/
struct nfs4_lockowner {
struct nfs4_stateowner lo_owner; /* must be first element */
};
@ -385,7 +451,14 @@ static inline struct nfs4_lockowner * lockowner(struct nfs4_stateowner *so)
return container_of(so, struct nfs4_lockowner, lo_owner);
}
/* nfs4_file: a file opened by some number of (open) nfs4_stateowners. */
/*
* nfs4_file: a file opened by some number of (open) nfs4_stateowners.
*
* These objects are global. nfsd only keeps one instance of a nfs4_file per
* inode (though it may keep multiple file descriptors open per inode). These
* are tracked in the file_hashtbl which is protected by the state_lock
* spinlock.
*/
struct nfs4_file {
atomic_t fi_ref;
spinlock_t fi_lock;
@ -410,7 +483,20 @@ struct nfs4_file {
bool fi_had_conflict;
};
/* "ol" stands for "Open or Lock". Better suggestions welcome. */
/*
* A generic struct representing either a open or lock stateid. The nfs4_client
* holds a reference to each of these objects, and they in turn hold a
* reference to their respective stateowners. The client's reference is
* released in response to a close or unlock (depending on whether it's an open
* or lock stateid) or when the client is being destroyed.
*
* In the case of v4.0 open stateids, these objects are preserved for a little
* while after close in order to handle CLOSE replays. Those are eventually
* reclaimed via a LRU scheme by the laundromat.
*
* This object is a superset of the nfs4_stid. "ol" stands for "Open or Lock".
* Better suggestions welcome.
*/
struct nfs4_ol_stateid {
struct nfs4_stid st_stid; /* must be first field */
struct list_head st_perfile;